A 27-year-old woman was sexually assaulted at knifepoint after two men got into her car while she was stopped at traffic lights.
She was on her way home to Leicester and had to drive through central London as a fire had closed part of the M25.
The woman was lost and it is unclear where the men got into her grey Peugeot 205 in the early hours of Monday.
She was forced to drive around before being thrown out of the car in Kensal Rise, north London.
Scotland Yard said the woman had been on a skiing holiday to France and had to stop at four fuel stations in London to ask for directions.
It was shortly after the fourth, at about 0200 GMT that one of the men got into the front passenger seat carrying a large knife and the second got into the back seat.
She struggled with the man in the front and suffered cuts to her hands.
The men told her they were going to Willesden Green.
After she was assaulted she was thrown onto the street at about 0400 GMT.
Both men were black and the first was aged in his mid-20s, with shoulder-length dreadlocks, wearing thick black round glasses and an imitation leather waist-length jacket.
The second man had a chubby face, brown eyes and wore a thick silver chain and a white and light blue basketball sweater.
Police are advising people travelling late at night to keep their car doors locked.